Map

To: common-lisp%SU-AI@USC-ECL

Subject: Map

From: Dick Gabriel <RPG%SU-AI@USC-ECL>

Date: Tue, 12 Apr 1983 16:10:00 -0000

Mail-from: ARPANET site SU-AI rcvd at 12-Apr-83 1212-PST

A user just pointed out that Common Lisp ought to discuss use of RETURN's,
GO's, and CATCH/THROW within MAP's. For the <your favorite adjective> soul
who comes to Common Lisp without benefit of Lisp Machine Lisp, there is
the bitter memory of the 1974 MacLisp manual recommending ``breaking out
of'' MAP's with RETURN's.
Aside from deciding whether one needs PROG's around the MAP, the typical
user is baffled because the behavior of MacLisp varies with interpreted
versus compiled code, and, within compiled code, it varies with the
presense versus the absence of the declaration (MAPEX T). I won't comment
on the bugs in the compiler with respect to this issue, but the upshot
from the user was that after the performance of MacLisp, the Common Lisp
manual ought to say something about this.
-rpg-